Chapter 10 Raceway Systems

Objectives Become familiar with the many different types of raceway systems. Understand the distinct uses of different types of raceways, based on the NEC. Cut, prepare, and join various types of raceway materials. Practice essential conduit bending techniques. Goodheart-Willcox Publisher

Raceway and Conduit Raceway Conduit Enclosed channel housing wires, cables, or busbars Conduit Tubing or channel connecting boxes

Electrical Metallic Tubing (EMT) Rigid conduit of galvanized steel Connected with setscrew and compression couplings Equipment grounding conductor

EMT Connections Goodheart-Willcox Publisher

Cutting Metal Conduit Hacksaw, reciprocating saw, pipe cutter Goodheart-Willcox Publisher

Reaming Metal Conduit Remove burr after cutting with deburring tool or files Burrs can damage insulation Goodheart-Willcox Publisher

Safety Note Metal shavings can cause serious eye damage Always wear safety glasses when working with metal materials Best habit is to wear protection at all times on jobsite

Bending Metal Conduit Field bend made on construction site Conduit bender Know minimum bend radius allowed by Code

Offset Bend Goes around obstruction or change in plane Opposing bends that change conduit elevation Shrink is shortening conduit due to bends Goodheart-Willcox Publisher

Offset Bend Goodheart-Willcox Publisher

Stub Bend 90° bend up or down to a box Goodheart-Willcox Publisher

Back-to-Back Bend Two 90° bends Ends of conduit pointing in same direction Goodheart-Willcox Publisher

Box Offset Two 5° bends align conduit with knockout hole Goodheart-Willcox Publisher

Saddle Bend Two 22 ½ bends and one 45 bend Around obstruction and returns to same elevation Goodheart-Willcox Publisher

Electrical Nonmetallic Tubing (ENT) Flexible corrugated plastic “Smurf tube” or “smurf” Connects with snap fittings or bonding cement Buried in concrete, behind walls Cannot be buried in soil or left exposed

Electrical Nonmetallic Tubing (ENT) Goodheart-Willcox Publisher; Carlon, Lamson & Sessions

Rigid Metal Conduit (RMC) Galvanized, smooth surfaces “Heavy-wall conduit” Connections with threaded fittings Serves as equipment grounding conductor Mast heads and exposed installations Goodheart-Willcox Publisher

RMC Connectors and Fittings Goodheart-Willcox Publisher

Code Alert RMC Bushings Section 344.46 Bushings to be used where rigid metal conduit enters a box, fitting, or other enclosure to protect wire from abrasion

Intermediate Metal Conduit (IMC) Heavy-duty, rigid conduit All atmospheric conditions and occupancies Joined with threaded fittings Can serve as equipment ground Goodheart-Willcox Publisher

Rigid PVC Conduit (PVC) Nonconductive polyvinyl chloride (PVC) plastic Lighter and easier to work than metal conduit Connect to metallic and nonmetallic boxes and conduit Heat to bend Goodheart-Willcox Publisher

Joining Rigid PVC Goodheart-Willcox Publisher

Flexible Metal Conduit (FMC) Spiral-wrapped metal conduit Greenfield Special couplings, locknuts, and bushings Bends in EMT or rigid conduit Goodheart-Willcox Publisher

Code Alert Grounding and Bonding FMC Section 348.60 Grounding and bonding requirements for FMC Grounding conductor must be used where vibration or flexibility Used as equipment grounding conductor in accordance with Section 250.118(5)

Liquidtight Flexible Metal Conduit Flexible steel or aluminum conduit Plastic sheath makes it watertight Goodheart-Willcox Publisher

Surface-Mount Raceway System of hollow tracks or channels, boxes, fittings Base and cover Mounts to wall or ceiling Electrical wiring and data cables Dry locations not subject to damage